Disk-type optical recording mediums are widely used. As recording density increases, various optical disk devices including CD, DVD, MOD (Magnetic Optical Disk), etc. have been developed. To reproduce a high-quality signal from an optical disk device, a laser spot should maintain focus and be tracked along a signal recording surface. However, the optical disk's rotation may cause surface vibration of the optical disk. If the surface vibration is more than an allowable amount, accurate focusing and tracking cannot be performed, which may cause intermittent interruption of the reproduced signal.
To cope with surface vibration of the disk, a surface vibration component is detected while the optical disk rotates once when the optical disk is first loaded, and compensation operations such as radial adjustment and defocus control are performed using the detected surface vibration component before the signal is reproduced from the optical disk. By performing these operations, when the signal is reproduced from the optical disk, focusing of the optical pickup device is performed within a focus search range that is initially set based on the initial detection of the surface vibration component for the optical disk. By performing these operations, when the signal is reproduced from the optical disk, focusing of the optical pickup device is performed within a focus search range which is initially set against surface vibration of the optical disk or deck
However, the surface vibration component of the disk is not constant over the entire area of the disk. In particular, the surface vibration component of the disk may have a greater value in the outer portion than in the inner portion of the disk. Accordingly, whenever the surface vibration component becomes greater than a predetermined allowable value, the process which detects a new surface vibration component generated during one rotation of the disk is repeated to determine a new focus search range and then the optical pickup device can be refocused. Such a focus repull-in operation may consume much time and generate intermittent interruption of reproduction of the signal from the optical disk.